Intestinal protein loss is a sign of failure of digestive function that often results from severe acute or chronic inflammatory lesions or from a disruption of chyle absorption and intestinal lymph flow. Early recognition of the syndrome and identification of the cause are important. A systematic diagnostic approach is required to rule out other causes of hypoproteinemia and to identify the underlying intestinal disease. Significant hypoalbuminemia (serum albumin <20 g/l) has been identified as a negative prognostic factor for chronic idiopathic enteropathies in the dog. Treatment of protein-losing enteropathy focuses on optimizing the diet and addressing the underlying intestinal disease. Acute oncotic support may be required in animals with severe panhypoproteinemia.